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What is the meaning of port 0 in netstat -an output in Windows? I'm asking about socket in Foreign address column:

0.0.0.0:0

I know that 0.0.0.0 address means, that host is listening on all interfaces, but what is the function of port zero?

Rafał Ryszkowski
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1 Answers1

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If you see this as the "Foreign" address, the meaning is slightly different – it's not about the interface; that would be the "Local" address.

All zeros in the "Foreign" column just mean that there is no remote address yet. The line represents a listening socket, which will accept connections from any address, any port. Those connections would be displayed as separate lines.

(From what I remember, in some early systems it used to be possible to create TCP sockets that would only accept connections from a specific host, a specific port, or both.)

grawity
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